var getChildForm = mnuService.GetChildNodeForm(menuName);
getChildForm usrCrtFrm = new getChildForm();
usrCrtFrm.Show();

public string GetChildNodeForm(string menuTitle)
    {
        var getMenuId = uow.Repository<MainMenu>().FindBy(x => x.MenuTitle == menuTitle).FirstOrDefault().MenuId;
        return uow.Repository<MainMenu>().FindBy(x => x.MenuId == getMenuId).FirstOrDefault().Url;
    }